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#1
11-01-00, 05:04 PM
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I have 2 lamp posts which were running 100 watt bulbs. These two posts are on the same circuit my two door lights are on. They also run 2 100 watt bulbs. I am adding a post and changing the lights on the other two posts. each post will run 3 60 watt bulbs and the door lights will stay at 2 100 watt bulbs. I am going to run the power wire to the first post continue on to to the second and then the third. will this work and can the breaker handle it at 20 amps. I am not sure how many amps it takes to run a 60 watt bulb, or 100 watt. I am using about 370 feet of standard wire.

#2
11-01-00, 06:01 PM
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Yes, easily (assuming nothing else is on this circuit). The combined load you mentioned is about 6 amps. You could triple this load with room to spare.

And although you didn't ask, I hope you know the GFCI and underground wiring requirements of this job. Not sure what you mean by "standard" wire, but "standard" NM-B can't be used outdoors.

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Calculation:
(2*100 + 3*3*60)/120 = 6.17 amps

You'll get about 5% drop in voltage over the 370 feet of 12 gauge wire (you're using 12 gauge, right?).

#3
11-01-00, 08:42 PM
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I suspect that you have more than just the lights you mentioned on that circuit. Past experience tells me you probably have a few receptacles on that circuit also. I agree with what John said you should be ok, just wanted to prompt you to look a little closer to see how much you have on that circuit. Just turn the breaker off and see what you lose power to in your home. I would check receptacles nearby as well as maybe some other light fixtures.

Are you installing receptacles on those post lights? If you are only running the post lights without any outside receptacles then a GFI control is not required. I feel it would be a good idea to install a GFI but it would not be required.

When you bury the wire, you might want to use type UF cable and bury it at least 18"

Hope this helps

Wg

#4
11-05-00, 08:08 AM
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quote:<HR>Originally posted by John Nelson:
Yes, easily (assuming nothing else is on this circuit). The combined load you mentioned is about 6 amps. You could triple this load with room to spare.

And although you didn't ask, I hope you know the GFCI and underground wiring requirements of this job. Not sure what you mean by "standard" wire, but "standard" NM-B can't be used outdoors.

----

Calculation:
(2*100 + 3*3*60)/120 = 6.17 amps

You'll get about 5% drop in voltage over the 370 feet of 12 gauge wire (you're using 12 gauge, right?).
<HR>

Hi John,

thanks for replying, I used 14 gage u3 underground wire and put it into under ground conduit 14 inches deep. I believe the code is 12" and 18" if your not using conduit. It came out real well the digging and trying to strip the u3 underground wire were the two hardest parts. again thanks

Tony Nazzaro

#5
11-05-00, 08:49 AM
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14 ga. wire is rated at 15 amps with a continuous load of 80% of rating or 12 amps. You should still be ok. UF cable is more difficult to strip than NM because it is rated for direct contact with the earth.

#6
11-05-00, 09:43 AM
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Stop! Stop! Stop! Stop! Stop!

Your post said you were going to use a 20-amp breaker.

DO NOT! DO NOT! DO NOT! DO NOT!

You used 14 gauge wire. Replace the 20-amp breaker with a 15-amp breaker immediately!

I know it's too late now, but you're going to lose about 10% of your voltage by using 14 gauge wire over this distance. A voltage drop of 2% is considered a normal design point. If you do something similar at a later time, increase the gauge of wire to compensate for the long distances.

#7
11-11-00, 05:41 AM
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quote:<HR>Originally posted by John Nelson:
[B]Stop! Stop! Stop! Stop! Stop!

Your post said you were going to use a 20-amp breaker.

DO NOT! DO NOT! DO NOT! DO NOT!

You used 14 gauge wire. Replace the 20-amp breaker with a 15-amp breaker immediately!

I know it's too late now, but you're going to lose about 10% of your voltage by using 14 gauge wire over this distance. A voltage drop of 2% is considered a normal design point. If you do something similar at a later time, increase the gauge of wire to compensate for the long distances.

[Hey John, did use a 15 amp breaker. I did not realize that I should have run 12 gage, I was actually told by Home Depot that the 14 gage would be fine for the run so that is what I went with. Do you forsee any problems??

/B]<HR>

#8
11-11-00, 05:21 PM
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You're fine. Sleep well.